1. Field of the Invention
This invention relates to a honeycomb structural design, and more specifically, to a sandwich core having rows of cells between layers at oblique angles to the layers.
2. Prior Art
In order to stop hypervelocity particles from penetrating a structure, several methods have been used to protect crucial components. First, a solid structure of sufficient thickness could stop a hypervelocity particle, however, the extra thickness would necessarily translate into extra weight. Another solution has been to provide a secondary xe2x80x9cbumperxe2x80x9d shield a distance from the structure to be protected. However, the spacing of a secondary shield apart from the protected structure leads to increased volume.
Various other efforts have been made to absorb the impact of high velocity and hypervelocity particles as taught in U.S. Pat. Nos. 5,848,767, 5,747,721, 5,686,689, 6,624,088, 5,601,258, 5,443,884, 5,221,087, 5,161,756, 5,102,723, and 5,067,388. Of these patents, U.S. Pat. No. 5,484,767 shows a spacecraft frame that utilizes a sandwich core, but the design of the core is not addressed, and is believed to be a traditional honeycomb design where the cell walls are substantially perpendicular to the layers. Other sandwich cores are shown in U.S. Pat. Nos. 5,624,088 and 5,443,884.
The traditional sandwich core is typically a honeycomb design having a top layer spaced apart from a bottom layer by a plurality of cells. The cells have a plurality of walls which are perpendicular to each of the layers. FIG. 5a of U.S. Pat. No. 5,443,884 illustrates a typical honeycomb sandwich core. These structures are often utilized in spacecraft design since they are stiffer than a single thin structure of the same mass.
The cells of traditional honeycomb sandwich cores are aligned perpendicularly to the facesheets, or layers. Accordingly, when a hypervelocity particle strikes and breaks through the outer facesheet, a plasma jet may form and be channeled through the cell. This jet will be directed by the cell perpendicularly to the inner facesheet. When the plasma jet breaks through the inner facesheet, the particle is then typically directed at the structure which was to be protected.
A need exists to provide a light weight and sufficiently strong sandwich core which may adequately deflect hypervelocity and high velocity particles from damaging a particular structure.
Consequently, it is a primary object of the present invention to provide a sandwich core which provides a sufficiently strong structure that is relatively light weight and deflects hypervelocity and high velocity particles in a more preferred manner.
Accordingly, the present invention provides a sandwich core comprising two faceplates separated by a plurality of cells. The cells are comprised of walls positioned at oblique angles relative to the perpendicular direction through the faceplates. The walls preferably form open cells and are constructed from rows of ribbons.